Objective To observe the effects of Ditan Yizhi Decoction on learning and memory ability,structure of hippocampal tissue,neuronal morphology of hippocampus,and the expression of endoplasmic reticulum autophagy-related protein FAM134B in hippocampal tissue;To explore the mechanism of its therapeutic effect on vascular dementia.Methods Totally 32 SD rats were randomly divided into sham-operation group,model group,donepezil group and Ditan Yizhi Decoction group,with 8 rats in each group.The model group,donepezil group and Ditan Yizhi Decoction group were prepared with a modified permanent ligation method of bilateral common carotid arteries to create a rat model of vascular dementia,the common carotid artery was separated in the sham-operation group,but not ligated.After modeling,the donepezil group was given donepezil hydrochloride,Ditan Yizhi Decoction group was given Ditan Yizhi Decoction,and the sham-operation group and model group were given equal volume of distilled water for gavage for 4 consecutive weeks.Morris water maze experiment was used to evaluate the learning and memory ability,HE staining and Nissl staining were used to observe the morphological changes of hippocampus,ultrastructure of hippocampal neurons was observed using transmission electron microscopy,Western blot was used to detect the protein expression of FAM134B and p-FAM134B in hippocampal tissue.Results Compared with the sham-operation group,the escape latency period was prolonged of the rats in model group,and the number of crossing the original platform and the duration of stay in the target quadrant was reduced(P<0.01),the gap between neurons in CA1 region of the hippocampus increased,the cell morphology was irregular,the boundaries were blurred,the neurons shrinked,the Nissl bodies dissolved and broke,the number decreased,the endoplasmic reticulum arrangement was scattered,mitochondria swelled and deformed,and the expressions of FAM134B and p-FAM134B protein in hippocampal tissue increased(P<0.01).Compared with the model group,the escape latency period of rats in donepezil group and Ditan Yizhi Decoction group were significantly shortened,and the number of crossing the original platform and the duration of stay in the target quadrant were increased(P<0.01),the morphology and quantity of neurons in CA1 region of the hippocampus were more regular,with a decrease in neuronal pyknosis,an increase in the number of Nissl bodies,and a reduction in dissolution and fragmentation,the swelling and deformation of the endoplasmic reticulum were restored,and the expression of FAM134B and p-FAM134B protein in hippocampal tissue increased(P<0.01).Moreover,the effects of Ditan Yizhi Decoction group were better than those of the donepezil group(P<0.01).Conclusion Ditan Yizhi Decoction can improve the learning and memory ability and the morphology of neurons in vascular dementia rats.The mechanism may related to increasing the expression and phosphorylation of FAM134B protein,thereby promoting endoplasmic reticulum autophagy.